From 4904231323789b7d5a0f6fa70fe7f55ee6fba109 Mon Sep 17 00:00:00 2001
From: Mingjie Xing <mingjie.xing@gmail.com>
Date: Fri, 3 Sep 2010 09:29:19 +0000
Subject: [PATCH] Fix shift count truncate problem for loongson.

From-SVN: r163799
---
 gcc/ChangeLog                                 |  6 ++++
 gcc/config/mips/mips.c                        | 17 +++++++++
 gcc/config/mips/mips.h                        |  7 ++--
 gcc/testsuite/ChangeLog                       |  4 +++
 .../mips/loongson-shift-count-truncated-1.c   | 35 +++++++++++++++++++
 5 files changed, 66 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/mips/loongson-shift-count-truncated-1.c

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 44c1da8e25b..dc4f9a0bf61 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2010-09-03  Mingjie Xing  <mingjie.xing@gmail.com>
+
+	* config/mips/mips.h (SHIFT_COUNT_TRUNCATED): Change the definition.
+	* config/mips/mips.c (mips_shift_truncation_mask): New function.
+	(TARGET_SHIFT_TRUNCATION_MASK): Define.
+
 2010-09-02  Richard Henderson  <rth@redhat.com>
 
 	* configure.ac (gcc_cv_as_cfi_advance_working): Use objdump
diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c
index 052e8051d25..3fe7f8b5961 100644
--- a/gcc/config/mips/mips.c
+++ b/gcc/config/mips/mips.c
@@ -16338,6 +16338,20 @@ void mips_function_profiler (FILE *file)
     fprintf (file, "\tmove\t%s,%s\n", reg_names[STATIC_CHAIN_REGNUM],
 	     reg_names[2]);
 }
+
+/* Implement TARGET_SHIFT_TRUNCATION_MASK.  We want to keep the default
+   behaviour of TARGET_SHIFT_TRUNCATION_MASK for non-vector modes even
+   when TARGET_LOONGSON_2EF is true.  */
+
+static unsigned HOST_WIDE_INT
+mips_shift_truncation_mask (enum machine_mode mode)
+{
+  if (TARGET_LOONGSON_2EF && VECTOR_MODE_P (mode))
+    return 0;
+
+  return GET_MODE_BITSIZE (mode) - 1;
+}
+
 
 /* Initialize the GCC target structure.  */
 #undef TARGET_ASM_ALIGNED_HI_OP
@@ -16546,6 +16560,9 @@ void mips_function_profiler (FILE *file)
 #undef TARGET_ASM_OUTPUT_SOURCE_FILENAME
 #define TARGET_ASM_OUTPUT_SOURCE_FILENAME mips_output_filename
 
+#undef TARGET_SHIFT_TRUNCATION_MASK
+#define TARGET_SHIFT_TRUNCATION_MASK mips_shift_truncation_mask
+
 struct gcc_target targetm = TARGET_INITIALIZER;
 
 #include "gt-mips.h"
diff --git a/gcc/config/mips/mips.h b/gcc/config/mips/mips.h
index 4dd86d4495c..74bf3d25c4c 100644
--- a/gcc/config/mips/mips.h
+++ b/gcc/config/mips/mips.h
@@ -2423,9 +2423,10 @@ typedef struct mips_args {
    (often extended) would be needed for byte accesses.  */
 #define SLOW_BYTE_ACCESS (!TARGET_MIPS16)
 
-/* Define this to be nonzero if shift instructions ignore all but the low-order
-   few bits.  */
-#define SHIFT_COUNT_TRUNCATED 1
+/* Standard MIPS integer shifts truncate the shift amount to the
+   width of the shifted operand.  However, Loongson vector shifts
+   do not truncate the shift amount at all.  */
+#define SHIFT_COUNT_TRUNCATED (!TARGET_LOONGSON_2EF)
 
 /* Value is 1 if truncating an integer of INPREC bits to OUTPREC bits
    is done just by pretending it is already truncated.  */
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 015ce4c4408..0a15006ba07 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2010-09-03  Mingjie Xing <mingjie.xing@gmail.com>
+
+	* gcc.target/mips/loongson-shift-count-truncated-1.c: New.
+
 2010-09-03  Daniel Kraft  <d@domob.eu>
 
 	PR fortran/44602
diff --git a/gcc/testsuite/gcc.target/mips/loongson-shift-count-truncated-1.c b/gcc/testsuite/gcc.target/mips/loongson-shift-count-truncated-1.c
new file mode 100644
index 00000000000..be52cf7dedc
--- /dev/null
+++ b/gcc/testsuite/gcc.target/mips/loongson-shift-count-truncated-1.c
@@ -0,0 +1,35 @@
+/* Test case for SHIFT_COUNT_TRUNCATED on Loongson.  */
+
+/* { dg-do run } */
+/* loongson.h does not handle or check for MIPS16ness.  There doesn't
+   seem any good reason for it to, given that the Loongson processors
+   do not support MIPS16.  */
+/* { dg-options "isa=loongson -mhard-float -mno-mips16 -O1" } */
+
+#include "loongson.h"
+#include <assert.h>
+
+typedef union { int32x2_t v; int32_t a[2]; } int32x2_encap_t;
+
+void
+main1 (int shift)
+{
+  int32x2_encap_t s;
+  int32x2_encap_t r;
+
+  s.a[0] = 0xffffffff;
+  s.a[1] = 0xffffffff;
+  /* Loongson SIMD use low-order 7 bits to specify the shift amount.
+     Thus V2SI << 0x40 == 0.  The below expression 'shift & 0x3f' will be
+     mis-optimized as 'shift', if SHIFT_COUNT_TRUNCATED is nonzero.  */
+  r.v = psllw_s (s.v, (shift & 0x3f));
+  assert (r.a[0] == 0xffffffff);
+  assert (r.a[1] == 0xffffffff);
+}
+
+int
+main (void)
+{
+  main1 (0x40);
+  return 0;
+}
-- 
2.30.2